Recent advances in uncooled detectors for thermal radiation or infrared (IR) radiation have resulted in thermal imaging systems with excellent properties. The most recent systems achieve a sensitivity that approaches the thermal limit and operate at speeds of 60 frames per second. More information about these systems can be found in P.W. Kruse, Proceedings 1996, SPIE Infrared Detectors and Focal Plane Arrays IV (1996), p. 34; C. Marshall et al., Proceedings 1996 SPIE Infrared Detectors and Focal Plane Arrays IV (1996), p. 23; and W. Radford et al. Proceedings 1996 SPIE Infrared Detectors End Focal Plane Arrays IV (1996), p. 82.
In these prior art systems images with high spatial resolution are obtained from arrays containing as many as 400 pixels per mm.sup.2 by reading electronic signals generated at each thermal radiation detector. In order to process this information, multiple transistors are integrated into each pixel and a separate device is used to display the image.
The prior art also teaches a direct view system where the thermal radiation is converted to a visible image thus eliminating the need for a complex readout system. Most advanced direct view systems use cantilever bimorph elements which deform in response to thermal radiation. Specifically, a microfabricated bimorph cantilever beam is constructed of two materials that have different coefficients of thermal expansion (CTE). A change in temperature causes the materials to expand or contract by different amounts causing the beam to bend or deform. This deformation can be observed by reflecting visible light, diffracting light from a number cantilevers or by employing any other well-known technique, e.g., from among the ones used in the field of Atomic Force Microscopy. Temperature changes on the order of 10.sup.-5 K. can be detected using bimorph cantilevers for such photothermal spectroscopy. Information about the basic concepts of photothermal spectroscopy using bimorph cantilevers is found in J. K. Gimzewski et al., Chemical Physics Letters, No. 217, 1994, pp. 589.
Further advances in bimorph cantilevers for photothermal spectroscopy are described in publications by J. R. Barnes et al., Nature, No. 372, (1994), pp. 79; P. G. Datskos et al., Applied Physics Letter, Vol. 69, (1996), pp. 2986 and P. I. Oden et al., Uncooled Thermal Imaging Using a Piezoresistive Microcantilever", Applied Physics Letters, Vol. 69, (1996), pp. 3277. These teachings detail how microfabricated cantilevers can be coated with metal to form a bimorph and used for photothermal spectroscopy with a power resolution of 1 nW/Hz.sup.-1/2. Furthermore, Oden et al. teach that two dimensional arrays of heat sensitive cantilevers can serve as thermal imaging devices. This photothermal technique has proved effective in measuring the power of radiation ranging from ultra-violet (UV) to IR with high sensitivity.
One of the most important parameters relating to thermal sensitivity in cantilever-based photothermal spectroscopy is the length of the beam. In most prior art devices the beam length ranges between 200-400 .mu.m. When such beams are placed in a two-dimensional array for imaging applications, the density of beams in the direction of the beam is limited to only a few per millimeter. It is possible to obtain a reasonable density of beams in the direction perpendicular to the cantilever. Unfortunately, developing a sensitive detection system for closely spaced sensors is difficult.